JP2516696B2 - Vacuum unit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vacuum unit having a mechanical booster.

(Prior Art) A vacuum unit in which a mechanical booster having a pair of rotors that synchronously rotate in a non-contact manner and a stator that is in a non-contact state with the rotors is connected in series with an auxiliary pump has been known. However, when vacuum reaction, vacuum drying, vacuum distillation, etc. are performed by such a vacuum unit, the process gas may be polymerized or solidified by being pressurized and heated inside the mechanical booster.

Therefore, when these polymers, etc., become particles and accumulate in the mechanical booster, dust is mixed into the mechanical booster by separating the gas and particles with a bag filter or cyclone filter. The method that does not do is adopted. However, the bag filter is troublesome to replace the filter element and
At the time of replacement, it is necessary to stop the vacuum exhaust system. Further, although the cyclone filter does not have such a defect, it is difficult to separate the fine particles having a fine particle size, and the fine particles may be deposited in the mechanical booster.

Such powdery particles may contact the rotors that need to be kept in non-contact with each other or between the rotor and the stator, and friction may increase power loss and may cause overheating or damage to pump components. Therefore, conventionally, the rotor and stator are disassembled and cleaned regularly, but not only the operating rate of the vacuum unit decreases, but also when particularly harmful gas is sucked or the vacuum system requires cleanliness. In that case, there is a problem that various measures must be taken to remove the pipe.

(Problems to be Solved by the Invention) The present invention solves the conventional problems as described above, and powder particles accumulated in the mechanical booster can be removed without disassembling the pump. The present invention has been completed to provide a vacuum unit capable of preventing troubles and improving the operating rate of the vacuum unit.

(Means for Solving the Problem) The above problem is an auxiliary using a seal liquid installed on the discharge side of a mechanical booster having a pair of rotors that rotate in a non-contact and synchronous manner, and a stator that is in a non-contact state with the rotors. This can be solved by a vacuum unit characterized in that the seal liquid of the pump or a liquid that can be mixed with the seal liquid is introduced into the suction port of the mechanical booster.

The auxiliary pump used in the present invention is a vacuum pump that uses a seal liquid, and examples thereof include liquid sealing vacuum pumps such as Elmo type and Nash type or vane type vacuum pumps, water ejectors, and oil rotary pumps. In the present invention, the sealing liquid of the auxiliary pump is guided to the suction port of the mechanical booster through the cleaning bypass pipe, and the performance of the sealing liquid is impaired even if it is mixed with the sealing liquid although the components are different from those of the sealing liquid. It is also possible to guide liquid without liquid to the suction port of the mechanical booster. The constituent members of the mechanical booster are required to have sufficient corrosion resistance against the sealing liquid and the like. The inside of the mechanical booster is cleaned by the liquid thus guided to the suction port, and the accumulation of powder particles can be prevented.

It is preferable that the introduction port of these liquids into the suction port of the mechanical booster is a nozzle facing the rotor side, but the invention is not necessarily limited to this. Since the flow in the cleaning bypass pipe is caused by the pressure difference between the pressure at the suction port of the mechanical booster and the pressure in the separator tank or oil pan installed on the discharge side of the auxiliary pump, the pump is generally installed in the cleaning bypass pipe. It is not necessary to provide it. However, pressurizing the seal liquid etc. with a pump,
Increasing the injection pressure from the nozzle is also effective for enhancing the cleaning effect.

In addition, the sealing liquid etc. introduced is made to have a vapor pressure lower than the pressure of the suction port of the mechanical booster to prevent diffusion into the vacuum system due to gasification of the liquid, and further prevent evaporation of the sealing liquid etc. to prevent rotor surface The washing can be always performed in a wet state. Further, in the present invention, the mechanical booster and the auxiliary pump can be cleaned with the seal liquid or the like while both are operating or only the auxiliary pump is operating. In short, it suffices to be able to generate a flow of sealing liquid in the cleaning bypass pipe,
When the pump is provided in the cleaning bypass pipe or when the liquid is supplied from the outside, the cleaning can be performed even when both are stopped.

 Hereinafter, examples of the present invention will be described.

(Example) (1) is a pair of rotors (2) that rotate synchronously without contact,
A mechanical booster having (2) and a starter (3) not in contact with the rotor (2), and (4) is a liquid-ring type auxiliary pump installed on the discharge side. The vacuum unit of this embodiment is for sucking a mixed gas of HCl, air and furan, and therefore the mechanical booster (1) has a rotor (2) and a stator (3) in contact with the gas.
Is made of partially stabilized zirconia with high corrosion resistance, the shaft seal uses a non-contact seal with a rotating ring made of SiC and a stationary ring made of carbon, and N ₂ gas purge is used. It has the feature of never leaking. As the auxiliary pump (4), an impeller having a partially stabilized zirconia and a casing made of alumina ceramics was used. A cyclone separator tank (5) for separating gas and liquid is installed at the discharge port of the auxiliary pump (4), the separated liquid flows through the circulation pipe (6), and heat exchange for cooling the strainer (7) and the sealing liquid. It circulates through the container (8) to the seal liquid inlet (9) of the auxiliary pump (4). A part of the separated liquid flows through the cleaning bypass pipe (10) and is guided to the suction port (11) of the mechanical booster (1).

First, when the auxiliary pump (4) is started and the suction pressure is saturated at around 200 torr, the mechanical booster (1) is operated and the vacuum degree of about 20 torr is repeated for 5 hours per batch. Then in 25 batches of operation, the mechanical booster (1) rotor (2),
Furan or a furan compound was deposited between the stators (3), the rotors contacted each other, and the mechanical booster (1) stopped due to overpower.

However, using the vacuum unit of the present invention, a suction pressure of 20
Bypass pipe for cleaning when saturated with 0 torr (10)
The valve (12) was opened and the inside of the mechanical booster (1) was washed for 10 minutes. Every batch was run, and even after 50 batches, the deposition of furan inside the mechanical booster (1) was continued. It was very small. In this case, the introduced liquid had the suction gas absorbed by the seal liquid.
An aqueous solution containing 10% HCl and several% furan, heat exchanger (8)
Keeps the temperature below 25 ℃, and the vapor pressure is kept below 20torr, which is the suction pressure of the mechanical booster (1), so there is no increase in the amount of gas due to the evaporation of the cleaning liquid and it affects the operation schedule. There was no.

In the above-mentioned embodiment, the cleaning is performed for each batch, but a sufficient effect can be obtained even if the cleaning is performed for every several batches or every ten or more batches. Further, although the HCl solution having a sufficient detergency for furan was used in the examples, the detergency can be further improved by mixing a solvent such as ethanol whose performance does not change even when mixed with the seal liquid. In addition,
Although the motor of the mechanical booster (1) is not started at the stage when the suction pressure is saturated, it is confirmed that the rotor (2) of the mechanical booster (1) is rotating at a low speed in the free running state due to the gas suction of the auxiliary pump (4). Was done.

(Effects of the Invention) As described above, according to the present invention, since the deposit inside the mechanical booster can be washed without the work such as disassembling, the trouble due to the deposit can be eliminated, and the operation can be performed. Since it can be cleaned inside, the operating rate of the vacuum unit can be improved.

In addition, the mechanical booster is of a dry type in which performance deterioration due to evaporation of the seal liquid cannot be avoided because it is in a vacuum even if the seal liquid is introduced into the pump, but according to the present invention, the vapor pressure of the seal liquid is sucked. When the degree of vacuum is sufficiently smaller than the pressure, the performance does not deteriorate, and conversely, the performance can be improved by improving the sealing property with the sealing liquid. Therefore, the present invention can be applied to not only the cleaning effect but also the performance improvement in the low vacuum region.

Therefore, as a vacuum unit which solves the conventional problems of the present invention, there is an extremely great contribution to the industrial development.

[Brief description of drawings]

The drawings are piping diagrams showing an embodiment of the present invention. (1): mechanical booster, (2): rotor,
(3): Stator, (4): Auxiliary pump, (11): Suction port.

Claims (1)

(57) [Claims] 1. A pair of rotors (2) that rotate synchronously without contact.
And a seal liquid installed on the discharge side of a mechanical booster (1) having a rotor (2) and a stator (3) in a non-contact state, mixed with the seal liquid of the auxiliary pump (4) or this seal liquid. A vacuum unit characterized in that the liquid to be obtained is guided to a suction port (11) of a mechanical booster (1).